I hit my head on this error, sometimes when my computer crashes, I cannot login to gnome after the reboot. The last couple of times i needed to reinstall because i could not find the error or what to do with the error messages.
re-emerge did not help so I guess its some configuration hiding somewhere thats messing things up.
if I'm killing pulseaudio just after I push the login button in gdm gnome starts, but (of course) with no audio.
Hope some can bring me a bit more light on this topic.

GNOME_KEYRING_CONTROL=/home/spawn/.cache/keyring-Jn7G3R
GPG_AGENT_INFO=/home/spawn/.cache/keyring-Jn7G3R/gpg:0:1
GNOME_KEYRING_PID=15521
GNOME_KEYRING_CONTROL=/home/spawn/.cache/keyring-Jn7G3R
GPG_AGENT_INFO=/home/spawn/.cache/keyring-Jn7G3R/gpg:0:1
GNOME_KEYRING_CONTROL=/home/spawn/.cache/keyring-Jn7G3R
GPG_AGENT_INFO=/home/spawn/.cache/keyring-Jn7G3R/gpg:0:1
SSH_AUTH_SOCK=/home/spawn/.cache/keyring-Jn7G3R/ssh
GNOME_KEYRING_CONTROL=/home/spawn/.cache/keyring-Jn7G3R
GPG_AGENT_INFO=/home/spawn/.cache/keyring-Jn7G3R/gpg:0:1
SSH_AUTH_SOCK=/home/spawn/.cache/keyring-Jn7G3R/ssh
Connection failure: Connection refused
Initializing tracker-miner-fs...
Initializing tracker-store...
Tracker-Message: Setting up monitor for changes to config file:'/home/spawn/.config/tracker/tracker-miner-fs.cfg'
Could not open log:'/home/spawn/.local/share/tracker/tracker-miner-fs.log', No such file or directory
All logging will go to stderr
Starting log:
File:'/home/spawn/.local/share/tracker/tracker-miner-fs.log'
Tracker-Message: Setting up monitor for changes to config file:'/home/spawn/.config/tracker/tracker-store.cfg'
Tracker-Message: Setting up monitor for changes to config file:'/home/spawn/.config/tracker/tracker-store.cfg'
Could not open log:'/home/spawn/.local/share/tracker/tracker-store.log', No such file or directory
All logging will go to stderr
Starting log:
File:'/home/spawn/.local/share/tracker/tracker-store.log'